Latching mechanism for telescoping lifting apparatus

ABSTRACT

1. A TELESCOPING LOAD LIFTING APPARATUS COMPRISING A FIXED MAST PORTION, A MOVABLE MAST PORTION AND LOAD BEARING PORTION WHEREIN SAID MOVABLE MAST PORTION AND SAID LOAD BEARING PORTION ARE INDIVIDUALLY AND CONJOINTLY VERTICALLY MOVABLE WITH RESPECT TO SAID FIXED MAST PORTION AND INDIVIDUALLY VERTICALLY MOVABLE WITH RESPECT TO EACH OTHER, LATCHING MEANS COMPRISING VERTICALLY SPACED APART UPPER AND LOWER LATCH LEVER MEANS, EACH OF SAID LATCH LEVER MEANS PIVOTALLY MOUNTED UPON SAID MOVABLE MAST PORTION, SAID LOWER AND UPPER LATCH LEVER MEANS BEING OPERABLY INTERCONNECTED WHEREBY SAID LOWER LATCH LEVER MEANS MAY SELECTIVELY ENGAGE AND DISENGAGE SAID LOAD BEING PORTION WHEREBY SAID MOVABLE MAST PORTION AND THE LOAD BEARING PORTION ARE VERTICALLY MOVED CONJOINTLY FROM THEIR MOST EXTENDED POSITION TO A PREDETERMINED ELEVATION, AND WHEREBY SAID UPPER LATCH LEVER MEANS MAY SELECTIVELY ENGAGE SAID DISENGAGE SAID FIXED MAST PORTION FOR SELECTIVELY SUPPORTING SAID MOVABLE MAST PORTION DURING FURTHER VERTICAL MOVEMENT OF SAID LOAD BEARING PORTION ABOVE SAID PREDETERMINED ELEVATION.

Nov. 19,1974

1 1 LATCHING MECHANISM FOR TELESCOPING LIFTING APPARATUS Frederick Stanley Rundle, Montour Falls, N.Y.

Assignee: Shepard Niles Crane & Hoist Corporation, Montour Falls, N.Y.

Filed: May 1, 1972 Appl. No.: 249,374

[75] Inventor:

US. Cl 187/73, 52/121, 212/128 Int. Cl B66b 5/16 Field of Search 187/73; 212/128; 52/121 References Cited UNITED STATES PATENTS Primary Examiner-M. Henson Wood, Jr. Assistant ExaminerMichael Y. Mar

Attorney, Agent, or Firm Parmelee, Miller, Welsh & Kratz [57] ABSTRACT A telescoping load lifting apparatus comprising a fixed mast portion, movable mast portion, and a loadbearing portion. The apparatus includes latching means comprising pairs of vertically spaced apart latch lever pairs. Each said pair is operably interconnected by tie rod means. Each latch lever includes a reaction roller means journally mounted at one end thereof, and each is pivotally mounted upon the movable portion. A lowermost latch lever is adapted to automatically and selectively engage and disengage the movable mast portion while an upper latch lever is adapted to automatically and selectively engage and disengage the fixed mast portion in a fashion whereby said load bearing portion and said movable mast portion may be conjointly elevated from floor level to a selected elevation thereabove.

4 Claims, 9 Drawing Figures mm 1 9|974 I PATENIE SHEET 2 BF 5 3.848.703

LATCHING MECHANISM FOR TELESCOPING LIFTING APPARATUS BACKGROUND OFTl-IE INVENTION A. Field of the Invention This invention relates to telescoping lifting apparatus and more particularly to a telescoping stacker crane or the like having an improved latching mechanism therefor.

B. Description of the Prior Art Telescoping lifting devices, such as stacker cranes,

ordinarily are comprised of three basic elements, namely, a fixed mast section extending vertically downwardly from a superstructure, an intermediate movable mast portion adapted to move vertically up or down the fixed mast portion within certain limits, and a loadbearing portion, such as a fork frame, adpated to move vertically up or down the movable mast. Where it is necessary for a telescoping mast to clear obstacles on a floor area such as machinery, vehicles, etc. or when the telescoping mast must be employed to load or unload vehicles of various kinds, it is necessary that the intermediate portion rise conjointly with the lower load bearing, e.g., forklift'portion, of the device at least until the intermediate portion reaches a height such that the device may readily pass over such obstacles or may readily pass into the bed of a vehicle to be loaded. It is also necessary that no part of the apparatus extend below the load bearing section in order to efficiently charge and discharge the device.

In the past, telescoping loading devices, particularly telescoping stacker cranes having forklift load bearing portions, have employed various designs and devices to control the vertical motion of the movable mast portion and fork frame portion to perform as indicated above. For example, elaborate tackle systems, roller chains, pulleys, and counterweights have been used. In addition, separate drive means were required for driving the intermediate mast portion to an out-of-the-way position. Due to the complexity of those designs, their use and construction was costly and space consuming and their maintenance was objectionably expensive.

U.S. Pat. No. 3,269,561 entitled Latching Mechanism for Telescoping Members discloses a stacker crane which eliminates the need for counterweighting mechanism, extra drive means, and the like and which has the ability to elevate the intermediate, or movable section of a telescoping mast to an out-of-the-way position together with the elevation of the load bearing section of the telescoping mast. There a latching mechanism is provided comprising laterally spaced apart latch lever pairs pivotally mounted upon the intermediate or movable mast section,which latches are activatedand deactivated for selectively engaging and disengaging the load-bearing portion of a crane whereby the load bearing, or fork section, and movable mast section of a stacker crane may be selectively raised or lowered together. The latching means of that patent includes a latch pivotally mounted upon a cross pin fixedly attached to the intermediate section of a telescoping structure. Each latch there is adapted to selectively engage and disengage the load-bearing and fixed mast portions of the telescoping structure. Actuating means for each latch are provided and include welded, or oth-' erwise rigidly secured, to the inside face of the load bearing section, a flat bar cam having an upper straight portion, an intermediate diagonal portion, and a lower straight portion. Additionally provided a short distance from the bar cam is a post cam likewise secured to the inside face of the load bearing section. The bar cam has a flat top portion and a beveled portion at the lower end thereof sloping downwardly and outwardly toward the inside wall of-a load bearing section. Located directly above the foregoing cams are a pair of like cams which are secured to the outer face of the fixed mast section of the telescoping structure. In that instance, the beveled portion of thelbar cam'is sloped downwardly and inwardly toward'the wall of the intermediate or movable mast section. Each such vertically spaced apart pair of bar and post cams serve to actuate a latching mechanism in a complex fashion as will be described hereafter.

In operation and construction of the patented device, exact and precise sizing and alignment of each of the various latching means elements is essential for proper operation thereof. For example, each latch lever may initially engage and support the intermediate mast portion for support by, and simultaneous elevation "with, the load bearing section while the telescoping structure is in its most extended position. Simultaneous elevation of both intermediate and load bearing sections may.

begin and continue to a predetermined level at which level a roller on each latch must simultaneously engage the lower beveled portion of a post cam fixed to the fixed mast portion of the telescoping structure. Contemporaneously therewith, the lower straight portion of a bar cam must enter between a pin pair located on a slide bar. Continued upward movement of the device must cause a roller on each latch toride over the beveled portion of a bar cam to the straight portion thereof whereby the latch may be forced slightly clockwise to thereby relieve pressure of the latch upon alatching bolt whereupon the bolt must be precisely withdrawn by the foregoing pin pairs on a slide bar riding up an oblique portion of a bar cam to thereby force the slide bar, and hence latching bolt, outwardly. At this point, the entire weight of the intermediate section of the telescoping structure is born by opposing members of bar cam pairs on the fixed and load-bearing sections of the telescoping structure. As upward motion of intermediate and load-bearing sections continues, a bar cam on the load-bearing portion must force each latch counterclockwise while in contact with a second roll on the latch. Upward motion continues until a first roll at an opposite end of the pivoting latch is forced into a seat ing position on the top of the post cam fixed to the fixed mast portion of the structure. At the same time, a bar cam fixed to the fixed mast structure must enter between the fore-mentioned pin pairs on the slide bar whereby an oblique portion of the cam may move the slide bar inwardly to thereby relatch, or reposition the latching bolt, in a groove provided in the latch from which it had been previously withdrawn. In the foregoing intricate fashion, an intermediate section of the telescoping portion is ultimately supported by the fixed portion of the telescoping structure, and the loadbearing section may pass to an even higher position. It will be appreciated here that each of the foregoing functions must be performed in an exact and precise fashion for efficient operation of the device. Slight misalignments of the telescoping structure, for example, due to the torque created by an overload on the loadbearing section may cause misalignment and malfunctioning of the'device. In addition, and primarily due to the withdrawing and accurate repositioning of a latching pin in a groove in each latch employed on a telescoping dev i ce,.rapid movement either, upwardly or downwardly is undesirable. Moreover, due to the multiplicity of parts and motions involved in a simple latching and unlatching operation, maintenance of the device, eg due to even minor bending of an element of the latching mechanism, is likely to be a significant problem.

This invention provides a latching mechanism for telescoping structures, such as stacker cranes and the like, which eliminatesthe need for counterweighting mechanisms, driving means, and the like. The invention further providesimproved means whereby an intermediate section of a telescoping mast may be elevated conjointly with the load-bearing section of a telescoping device to an out-of-the-way position clear of floor obstructions, and in a fashion whereby movable or portable stations such as a truck bed, may be efficiently loaded. The invention additionally provides an improved mechanism for establishing supporting connection between the intermediate section of a telescoping device and the fixed mast section and load-bearing sections thereof. Moreover, the invention specifically provides an improved latching means of a simplified and fail-safe nature for telescoping devices, particularly for stacker cranes. An important additional provision of the invention is that of a latching mechanism having fewer moving parts than latching mechanisms heretofore known. Additional advantages and features of the invention will become apparent as this specification proceeds.

SUMMARY OF THE INVENTION This invention provides an improved telescoping lifting apparatus including a fixed mast portion, at least one movable intermediate mast portion, and a movable load-bearing portion. An improved latching means is provided for selective interconnections between respective portions thereof including pairs of vertically spaced-apart pivoting latches. Each latch pair is operably interconnected by tie rod means or the like which are normally maintained in constant tension; Each latch lever includes'a reaction roller journally mounted at an outer end thereof, and each latch lever is pivotally mounted at selected positions on the intermediate movable mast portion of the telescoping structure. Each lower latch lever ofa spaced-apart latch lever pair is adapted to selectively engage and disengage, automatically and mechanically, the load bearing portion portion in a fashion whereby thelo'ad-bearing portion and movable mast portions may be conjointly elevated from the telescoping devices most extended, or floor level position, to a selected location thereabove. Each upper latch lever of alatch lever pair is adapted to automatically and selectively engage and disengage the fixed mast portion in a fashion whereby said intermediate mast portion may be selectively supported thereby and whereby the load-bearing portion may elevate to a higher position while the intermediate mast portion is so supported. Preferably, a reaction rail means is provided forengaging and guiding said upper latch lever of a latch lever pair which reaction rail is fixed, as by welding, to the fixed mast portion of the telescoping device. Most preferably, the reaction rail means terminates in an arcuate fashion at the uppermost end thereof, whereby an upper latch lever pivotally mounted 1 upon the intermediate mast section may smoothly and efficiently pass thereover for accurate and efficient support thereof by said fixed mast portion. Most preferably, laterally spaced-apart pairs of latch lever pairs operably interconnected by tie rod means are employed in telescoping load lifting devices according to the invention. Other. advantages and details of the invention will become apparent by reference to the appended drawings and as the following more detailed description thereof proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 8 is a detailed illustration of a preferred upper I latch lever according to the invention; and

FIG. 9 is a sectional view taken along line lX-lX of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference now to FIG. 1, a stacker crane including the latching means of the invention shown in partial sectional elevation in its most-extended, or telescopic, form. The stacker crane includes generally a fixed mast portion 2, an intermediate, movable mast portion 4, and a load-bearing portion 6 including forklift means 8 extending laterally therefrom- The entire telescoping crane depends downwardly from a superstructure 10 which usually comprises a movable bridgework, or trolley, including wheels 12 adapted to ride upon rails 13 for transverse movement of the crane. In many cases, an additional bridgework, or trolley is provided for permitting transverse movement of the crane at right angles to that illustrated in the FIG. 1 for providing a more mobile and versatile crane. Fixed mast portion 2 is rigidly affixed in a conventional fashion to a suitable rotary apparatus such as a slewing ring means 5 for providing rotating motion to the crane. On each side of intermediate movable section 4 is a reaction rail 14 which serves as a track for reaction roller sets 16 and 17 each of which respectively comprise three individual journally mounted roller bearings. That rollertrack or rail combination serves to maintain the respective intermediate and load bearing sections in proper alignment during relative vertical movement thereof. In a similar fashion, on each side of fixed mast portion 2 is provided a reaction rail 20 which rail functions as a track for a lowermost set of reaction rollers 22 and an uppermost pair of reaction rollers 24. Roller set 22 is affixed to intermediate mast portion 4 at a point at or near the lower end of rail 20 which extends downwardly substantially the length of fixed mast portion 2. Reaction rail 20 additionally serves as a track for a reaction roller 32 on upper latch lever 30 of the latching mechanism and, in afashion more fully explained hereafter, participates in actuating the latching means "of the invention. Vertical movement of thernovable portions of the telescoping lifting device shown inrFIG. l

is controlled by a cable 26 wound upon a power driven quence of a telescoping apparatus comprising a stacker crane according to the invention is shown. In FIG. 2, the telescoping stacker crane is shown in its most extended position whereat load bearing portion 6 having forks 8 extending therefrom are at floor level. At this point, upper latch lever 30, through roller 32 is abutting reaction rail 20, while lower latch lever 40 of the latch lever pair extends through an appropriate opening (not there shown) in the side wall of intermediate movable mast portion 4. It will be understood of course that while the following description is made with refer-. ence to a single vertically spaced apart latch pair comprising upper and lower pivoting latch levers 30 and 40, respectively, that it is especially preferred that laterally spaced apart pairs of such latch lever pairs are preferred in telescopic constructions according to theinvention. Lower pivoting latch lever 40 is pivotally attached to movable intermediate portion 4 through pivot pin 41 fixed to the side wall thereof. The pivotal attachment is most preferably made at a point vertically adjacent the top of the frame members of load bearing portion 6 whereby the lowermost portion, or underside, of latch'40 may substantially rest upon or abut that frame in its most extended position. Activation of reel 27 for raising loadbearing portion 6 of the apparatus will urge the frame portion thereof against the bottom of lower latch 40 and thereby urge a reaction roller32 on upper pivoting latch 30 against rail formaintaining tie rod means 50 in tensiornMore precise and preferred descriptions of the preferred pivoting latch constructions and tie rod interconnections are presented hereafter but suffice at this point to say that upper latch lever is pinned eccentrically or is pivotally mounted eccentrically by means of a journaled pin connection 31 to an uppermost portion of intermediate movable portion 4 of the stacker crane. As upward vertical motion of load bearing portion 6 of the stacker crane continues, intermediate portion 4 thereof will be carried upwardly conjointly with the load bearing portion 6 by means of forces exerted thereon through lower pivoting latch levers at the pivot connections in the sidewalls thereof. v Continued upward motion of load bearing portion 6 of the stacker crane in FIG. 2 will causeroller 32 of upper latch lever 30 to travel the length ofreaction rail end portion 21 of rail 20, lower latch lever 40, due to the forces exerted thereon by tie rod 50 as upper latch lever 30 rotates about pivot pin 31, pivots about pivot pin 41 and is withdrawn through sidewall of intermediate movable mast portion 4. Continuedraising of load bearing section 6 of the telescoping structure will result in the abutment of roller 42 on lower pivoting latch 40 against the inner face of the frameaof load bearing portions 6. The forces exerted on roller .42 maintain connecting rod 50 in tension to thereby lock an upper latch lever 30 interconnected therewith in place on rail end portion 21 as shown in FIG. 3. At that point, intermediate movable portion 4 of the telescoping structure is supported efficiently and effectively the .latching mechanism. It will be remembered thata pair of latching mechanisms arepreferably provided laterally spaced apart in the structure. ln'one embodiment (not shown), a rail similar to rail 20 and serving as a track for a roller 42, is preferably provided. fixedly sei cured to the inner face of load bearing portion 6 for more effectively guiding continued Ivertical motion of load bearing portion 6 of the telescoping structure.

In FIG. "4, load bearing portion 6 is at its most ele- I vated position. At that point, tie rod 50 is still maintained in tension by the forces exerted thereon through cal motion of the telescoping structure. It will'be appre ciated here that the invention through novel latching means including the combination of vertically spaced apart pivoting latch levers interconnectedby a tie rod in tension, provides a more efficient and fail safe latching and support means for telescoping structures of the 7 type described. The latching means and support transfer means comprises amore simplified Iconstruction and includes essentially only a pair of moving parts, namely upper and lower pivoting latch means-Moreover, the latching mechanism will function even when .the crane sections are substantially misaligned. In addition, speed of elevation orv descent of a crane mechanism embodying the invention will not substantially effect the efficient operation of the latching mechanism.

respective upper and lower ends thereof. Each of the threaded portions 51 and 52 is adapted to threadably engagerespective upper and lower clevises 53 and 54. Each of the clevises is pivotally attached to a respective pivoting latch member in a conventional fashion as through pivot pins 47 and 57. Most preferably,

threaded portions 51 and 52 are threaded in opposite hand whereby rotation of rod 50 may adjustably fix the distance between pivot pins 47 and 57. To that end a hex nut 55 is provided fixed, as by welding; to tie rod 50 which provides a convenient means for grasping and rotating the tie rod. Lower pivoting latch lever 40 and upper pivoting latch lever 30 are journally mounted on the side wall portion of intermediate movable mast portion 4 through heavy-duty pivot pin connections 31 and 41 respectively. Preferred pivot-pin constructions will be more fully described hereafter. It is sufficient to state at this point that heavy-duty pivot pin connections are preferred since those connections have a loadbearing function.

Pivoting latch levers 30 and 40 are operably interconnected through tie rod 50 in a fashion whereby each of the levers is urged to pivot in a like direction when rod 50 is in tension. For. example, as load-bearing portion 6 is raised conjointly with intermediate movable mast portion 4, a force, designated F is exerted upon the underside of lower pivoting latch 40 urging the latch to rotate in a counterclockwise (as shown) direction. In that fashion, rod 50 is placed in tension and urges latch 30, pinned eccentrically to movable mast portion 4 through pivot pin 31 at an end thereof to also rotate in a counterclockwise direction. Placing rod 50 in tension by means of exerting a force F upon the base of lower pivoting latch 30 will, of course, urge reaction roller 32 against reaction rail 20 at a force, designated F in FIG. 5, as upper pivoting latch 30 is urged to rotate about pivot pin 31. As vertical motion of load-bearing portion 6 and intermediate movable portion 4 of the telescoping load lifting assembly continues, for example, as indicated in FIG. 3, roller 32 may continue to travel along rail 20 until it reaches end portion 21 of rail 20 whereat the forces exerted by rod 50 in tension may result in the passing of roller 32 over the top portion 21 of rail 20 to thereby rotate latch 30 about pivot pin 31. in that fashion lower pivoting latch lever 40 likewise may rotate about its respective pivot pin 41 whereby the lower latch 40 may rotate as shown in phantomin in FIG. through a slot or opening 60 provided in a side wall or in the front wall (as indicated) portion of intermediate section 4 to a point where load-bearing portion 6 may pass over the suspended intermediate portion 4. At that point, reaction roller 2 journally mounted at an end of lower pivoting latch 40, remote from its tie rod connection, may be urged or abut against the inner face of load-bearing portion 6 of the telescoping assembly during further vertical movement thereof (FIG. 5).

With reference now to FIGS. 6 and 7, a preferred lower latch lever construction useful in the invention is illustrated. There, a lower latch lever 40 comprises a generally triangular configuration and includes at one end thereof a pivotally mounted clevis 54 for engaging a tie rod 50. Clevis 54 is journally mounted with respect to lower pivoting latch lever 40 through a yoke-like attachment to a pivot pin 47 passing through an appropriate bore in one end thereof. Pin 47 is maintained in position and in contact with clevis 54 in conventional fashion as through retaining rings 48 in circumferential grooves 48a in the ends thereof. Atthe end remote therefrom on the lower pivoting latch lever 40 is a roller bearing 42 journally mounted upon a shaft or axle 43 operably mounted in bifurcated mounting bracket including forked portions 45. The entire latch lever mechanism 40 is journally mounted upon a sidewall portion 4a of intermediate movable mast section 4 in a conventional fashion. For example, a mounting bracket 7 is provided fixedly attached as by welding to ing rings 46 or the like in a circumferential groove 46a at the end thereof.

With reference now to FIGS. 8 and 9, a preferred construction for an upper pivoting lach 30 useful in the invention, is illustrated. Upper ipvoting latch 30 is journally mounted upon a side wall portion 4a of intermediate movable mast portion 4 by conventional means including a heavy duty pivot pin 9 rigidly secured as by welding to side wall portion 4a. A roller bearing means 34 or the like is provided within upper latch lever 30 and at one end thereof for pivotal movement of latch lever 30 about pin 31. Here again the entire upper latch is maintained in position on pivot pin 31 by a retaining ring means 36 in circumferential groove 37 on pivot pin 31. Clevis 53 on tie rod 50 is pivotally connected to upper latch lever 30 in conventional fashion as by passing through an appropriate bore therein. Pivot pin 57 is maintained in position by means of retaining rings 58 in circumferential grooves 59 at the ends thereof. Pivot pin 57 is located in the body of upper latch lever 30 at a point intermediate the ends thereof whereby tension in tie rod 50 will urge rotation of the latch lever in a like direction as that of lower latch lever 40.

At an end of upper latch lever 30 remote from pivot pin 31, about which the entire latch lever may rotate, is provided a roller 32 adapted to abut rail 20 fixed to fixed mast portion 2. Roller 32 is adapted to rotate about a shaft 33 in a conventional fashion as previously described with respect to roller 42 on lower latch lever In accordance with the patent statutes, the foregoing has described the invention, the best presently known and certain preferred emboidments thereof. It should be expressly understood, however, that the invention is not necessarily limited to the specific embodiments disclosed'therein, but may be variously practiced within the scope of the appended claims.

What is claimed is:

l. A telescoping load lifting apparatus comprising a fixed mast portion, a movable mast portion and load bearing portion wherein said movable mast portion and said load bearing portion are individually and conjointly vertically movable with respect to said fixed mast portion and individually vertically movable with respect to each other,

latching means comprising vertically spaced apart upper and lower latch lever means, each of said latch lever means pivotally mounted upon said movable mast portion,

said lower and upper latch lever means being operably interconnected whereby said lower latch lever means may selectively engage and disengage said load bearing portion whereby said movable mast portion and theload bearing portion are vertically moved conjointly from their most extended position to a predetermined elevation, and whereby said upper latch lever means may selectively engage and disengage said fixed mast portion'for selectively supporting said movable mast portion duringfurther vertical movement of said load bearing portion above said predetermined elevation.

2. The apparatus as set forth in claim 1 wherein said lower and upper latch lever means are operably interconnected by tie rod means and wherein said tie rod means is normally under tension for urging said respective latch lever means to pivot in a like direction.

3,848,703 9 10 3. The apparatus as set forth in claim 1 wherein said telescoping load lifting apparatus includes laterally fixed mast portion includes rail means affixed thereto s aced a art airs of said verticall s aced a art u er adapted to serve as a track for roller means at one end p p p y p p pp of said upper latch lever means. and lower latch lever means 4. The apparatus as set forth in claim 1 wherein said 5 

